1. Field of the Invention
This invention relates to fusion reactor systems, and more particularly, to a compression hub employable therein in cooperative association with a plurality of magnets.
2. Description of the Prior Art
One form of fusion reactor that has been proposed for use by the prior art is the so-called Tokamak-type reactor. In accordance with the mode of operation of this type of reactor, thermal power is generated as a consequence of the ignition of plasma. There exists, however, in this type of reactor not only a need to ignite the plasma, but also a need for effecting control levels to ignition.
One technique which has been proposed for use for purposes of effecting control over the plasma, is that of magnetic confinement. More specifically, it has been proposed to employ for this purpose a plurality of superconducting magnets operating at cryogenic temperatures. Through the use of such magnets, it is possible to attain intense magnetic fields of a strength sufficient to effect the desired confinement of the plasma.
To produce the desired result, the superconducting magnets are preferably arranged relative to each other so that they extend outwardly from a common point, in a manner similar to that of the spokes of a wheel. These magnets generate intense forces, tending to draw them together to the common point. Thus, there is a need created to provide means operative to resist the forces tending to draw the magnets together. One means contemplated for use for this purpose is a compression hub.
One form of a compression hub, which is suitable for use for the aforedescribed purpose, comprises the subject matter of Gaines patent application, Ser. No. 832,492, filed on Sept. 12, 1977, and assigned to the same assignee as the present invention. As discussed in the Gaines patent application, a compression hub in order to be suitable for use for the purpose described above must be susceptible to being cooled to the same relative temperature as the superconducting magnets, i.e., to cryogenic temperatures. In addition, this cooling of the compression hub must be capable of being accomplished while at the same time insuring that the structural adequacy of the compression hub is maintained.
Regarding the matter of cooling, as set forth in the afore-referenced Gaines application, the normal operating temperature range for the superconducting magnets is 4.2.degree. to 4.9.degree. kelvin. To achieve this range of temperatures, the magnets are preferably cooled by liquid helium, which boils at 4.2.degree. kelvin at atmospheric pressure. Because of the criticality of the operating temperature, it is necessary that the compression hub, which is cooperatively associated with the superconducing magnets, be cooled also to the same temperature as the magnets. Otherwise, heat transfer in the form of a heat loss could take place between the compression hub and the magnets cooperatively associated therewith whereby the operating effectiveness of the magnets would be seriously impaired.
Not only is it necessary that the operating temperature of the compression hub be maintained at the same operating temperature as the superconducting magnets, but also it is important that the compression hub be capable of being cooled to the desired operating temperature of 4.2.degree. kelvin in a relatively short period of time. One method of effecting the desired cooling of the compression hub is to depend on the cooling effect of the magnets to remove heat from the compression hub. However, this could take an inordinate amount of time to achieve, which would be totally unacceptable from the standpoint of how long it takes to render the system operative, particularly in a start-up situation. The reason for this, as discussed in the aforesaid Gaines patent application, is that at these very low temperatures the thermal gradient between the compression hub and the magnets cooperatively associated therewith is so small that virtually no cooling of the compression hub is effected. It, therefore becomes necessary to supply coolant to the compression hub itself. More specifically, fluid flow paths must be established for coolant in the compression hub. However, as noted previously hereinabove, the coolant flow paths in the compression hub must be provided in such a manner as to not adversely affect the structural adequacy of the compression hub, i.e., the ability of the compression hub to resist the forces tending to draw the magnets together to a common point.
In the aforementioned Gaines patent application, one form of compression hub, which fulfills the above stated requirements for a compression hub employable in a Tokamak-type fusion reactor system, has been described and illustrated. The present invention on the other hand, which constitutes the subject matter of the instant application, is directed to an alternative form of construction for a compression hub. It is contemplated that a compression hub constructed in accordance with the present invention would be employed in lieu of the compression hub described in the co-pending Gaines patent application.